Blending continuous filament yarns

ABSTRACT

Intimate filament-to-filament blending of continuous filaments is accomplished by laying up at least two fibrillated striated films and converting the laid up structure to a coherent yarn end by twisting or by entanglement. The method can be used to blend, e.g., yarns of different color, different denier or different shrinkage potential.

United States Patent Kim I [54] BLENDING CONTINUOUS FILAMENT YARNS [72] Inventor: Charles W. Kim, Wilmington, Del.

[73] Assignee: Hercules Incorporated, Wilmington,

Del.

[22] Filed: June 9, 1970 [21] Appl. No.: 44,841

[52] US. Cl. ..57/157 R, 28/D1G. l [51] Int. Cl ..D02g 3/02, D02g 3/38 [58] Field of Search ..57/31, 140, 155, 157; 28/1,

- 28/DIG. 72', 225/3, 97

[56] References Cited UNITED STATES PATENTS 4/1970 Prevorsek et a1 ..28/D1G. 1 X Greene ..28/DIG. 1 UX Kim ..28/DIG. 1 X

[ 51 Aug. 1, 1972 Rasmussen ..57/157 3,460,336 8/1969 Collingwood et a1. ..57/34 X 3,484,916 12/1969 Johnstone .Q ..28/1 UX 3,332,228 7/1967 Chill. ..57/155 3,474,61 1 10/ 1969 Suzuki et al. ..57/31 3,402,548 9/ 1968 Wininger et a1 ..51/157 X 3,470,595 10/1969 Goppel ..28/1 X Primary Examiner-Donald E. Watkins Attorney-John W. Whitson [57] ABSTRACT Intimate filament-to-filament blending of continuous filaments is accomplished by laying up at least two 'fibrillated striated films and converting the laid up structure to a coherent yarn end by twisting or by entanglement. Themethod can be used to blend, e.g., yarns of different color, different denier or different shrinkage potential.

v 12 Claims, 2 Drawing Figures PATENTEDA E 1 I973 FIG. I

CHARLES W. KIM INVENTOR ATTORNEY BLENDING CONTINUOUS FILAMENT YARNS This invention relates to the blending of synthetic filaments. More particularly, it relates to a method for uniformly blending into a yarn, continuous synthetic filaments of different properties.

In the textile processing industries, there are many occasions when it is desirable to blend fibers of different types to achieVe unique combinations of properties. The methods employed for this purpose usually involve initially blending a plurality of short length staple fibers and subsequently spinning a blended yarn from this mixture. An example of this is found in the preparation'of the well known polyester--cotton blends I employed in a great number of wash and wear apparel items.

However, practical processes for accomplishing blending .on a filament-to-filament level of intimacy have been limited heretofore to staple length fibers such as the polyester-cotton type cited above. No truly practical process for accomplishing intimate blending of continuous filaments has yet been devised. It is the object of this invention to provide a method whereby an intimate filament-to-filament level blending of continuous filaments from different sources can be effected.

The method of the invention broadly comprises providing at least two fibrillated, linearly striated films from different sources, superimposingsaid films upon one another, and converting the resulting superimposed structure into a yarn.

The concept of fibrillatinga striated film to prepare a low denier continuous monofilament beam has only recently been introduced to the art. In this procedure, a thin, longitudinally oriented, striated film having thick ribs'a'nd thin webs is subjected to mechanical working, whereby the film is split in the thin webs, leaving the relatively thick ribs intact in the form of continuous filaments. Depending upon the degree of working effected upon the film, the splitting along the webs can be total to separate each of the ribs completely from its neighbors. In most cases, however, the splitting will be stopped short of total separation, leaving small, fibrillar these references can be employed in carrying out this invention.

The invention is illustrated in the attacheddrawing in which FIGS. 1 and 2 depict different techniques for carrying out the process.

As shown in FIG. 1 of the attached drawing, fibril lated films l and 2 from different sources are drawn off mill rolls 3 and 4 respectively by pull rolls 5 and 6. The films are drawn over bowed rolls 7 and 8 which cause the filaments to separate slightly from one another and the two films are superimposed by cooperation between pull rolls 5 and 6 and pull rolls 9 and 10. The transverse displacement of the filaments caused by their passing over bowed rollers 7 and 8 provides space between the filaments of one layer for those of the otherlayer to fit in, thus assuring intimate blending.

ment and gathered into a package 17. In this procedure, the surface speed of pull rolls 5 and 6 is about 5 to 10% greater than that of pull rolls 9 and 10 to maintain zero tension on the fibrillated films fed to the air jet.

Twisting or entanglement serves the dual purpose of transforming the flat, superimposed filamentary struc-' ture into a conventional yarn shape as well as imparting coherency thereto to maintain the individual filaments in their filament-to-filament state of blending.

The advantage of employing a fibrillated film in filament blending according to the present invention is that filaments from one source are presented to those from another source in a beam of single filament thickness. In previous attempts at blending continuous filaments, yarnshave been employed and it has been necessary to open these yarns to allow the filaments from different sources to intermix, following which the mixed filaments are reformed into a yarn. It seldom happens, however, that the yarns are opened and the filaments separated sufficiently to allow the desired in-' timate degree of filament blending. By contrast, when proceeding according to the process of this invention, each of the fibrillated film sections laid up to prepare the blended yarn is comprised of a plurality of continuous filaments aligned in parallel arrangement in a single layer. When one of these is opened in the manner described above and superimposed upon another, which is likewise opened, the probabilities favor a filament from one layer being located adjacent to two filaments from the other layer, resulting ina very intimate blending of the components, i.e., substantially a filament-to-filament blending.

As stated, the method of the invention is employed with filaments from different sources to effect blending to a desired balance of properties to produce a desired effect. For example, the different sources can be entirely different thermoplastic materials having different shrinkage potentials. When these yarns, following blending, are subjected to shrinkage conditions, they develop bulk due to the resulting differential between the length of the components.

The filaments from different sources can be of the same material but of different denier, e.g., a relatively heavy denier and a relatively light denier. Such a combination changes the hand and the appearance of the finished yarn compared to a yarn having consistent filament denier throughout.

Yarns of different colors can be blended by this method. In the blending of colors, uniformity of blending is especially desirable. Thus, the method of the invention offers a particular advantage in this application. Many unique combinations and aesthetic effects are possible with colors blended according to this embodiment of the invention.

The striated films employed to prepare the continuous filaments employed in the process of this invention are longitudinally drawn at least 100 percent, and preferably 400 to 800 percent to yield oriented filaments. Orientation serves to increase the longitudinal strength, shrinkage potential, durability, and other properties of the filaments, as is previously known in the synthetic fibers art.

As stated above, one of the features for which the invention can be used is to provide bulk by means of differential latent shrinkage of the two components. These latent properties can be developed by passing the twisted yarn through an appropriate heating oven, or over an appropriate heated plate or roller unde'r'little or no tension according to methods already known to the art. In this manner, the more shrinkable filaments are caused to shrink and create bulk in the yarn.

If the yarn components do not possess latent crimpability due to shrinkage, the yarn can be bulked or crimped by conventional means such as the stuffer box technique, the fluid jet technique, by heat setting of a false twist, or any other method known to the art.

The invention is illustrated by not limited by the following examples.

EXAMPLE 1 A striated film was prepared from a commercial polypropylene'having an intrinsic viscosity of 2.2. A second striated film was prepared from the same polymerwhich had been subjected to a controlled thermal degradation at about 290 C. under high shear conditions, to narrow its molecular weight distribution. Both films were linearly drawn 6X and fibrillated according to the procedure of US. Pat. No. 3,494,522 to form a network structure of continuous filaments held together by very fine fibrils.

' The filaments'resultingfrom fibrillation of theconventional polypropylene were found to shrink about 6 percent in boiling water after minutes. That prepared from the visbroken polymer shrank percent when subjected to the same test.

A l-inch wide strip of the fibrillated degraded film was superimposed on a l-inch wide strip of the unmodified non-visbroken film, which was also transversely opened, and thetwo weretwisted by passing them through an air jet. A twisted, coherent yarn of about 1,000 total denier was recovered. This yarn was gathered into skeins which were immersed in boiling water for 5 minutes. Upon removal from the water and drying, the yarn was found to have increased in bulk to a total denier of about 1,200. The bulk level of the yarn appeared to be substantially homogeneous throughout.

- EXAMPLE 2 Afibrillated, striated film of polypropylene containing a blue pigment was superimposed upon a natural color fibrillated, striated'film of polypropylene containing no pigment and this mixture was converted into' a yarn by twisting. The resultant blue-white heather effect was aesthetically pleasing and the coloration effect was uniform throughout the length of the filament.

The method of the invention can be used to blend filaments in any ratio, from about 15/85 to 50/50 by weight. Normally, blending is at a 5 0/50 ratio, whichis conveniently accomplished by laying up two layers of equal width fibrillated film having equal striations per inch. To prepare other ratios, equal widths of film can be emPloyed having the same number of striations but having striations of different denier per filament. To blend uniformly under this condition, the filaments having lower dpf must be laterally displaced from one another, e.g., by use of bowed rollers as discussed above, by a distance at least equal to the diameter of the individual filaments on the larger filament layer. Thus, for example, a film strip having 20 dpf ribs can be superimposed with an equal opened width of a film having'lO dpf ribs to form a yarn having the components blended in a 2]] ratio.

Other ratios can also'be prepared by employing a second layer of the component desired in the larger percentage. The larger component layers will sandwich the smaller component and the filaments of adjacent layers will be adjacent one another in a substantially homogeneous manner. This method is used when it is not desirable to vary the size of the individual filaments.

Yarns havinga total denier of to 500 and up tO about 1,5.00-strands, can be prepared according to the process of this invention. The total denier depends on the thickness and width of the films laid up to prepare other singles ,yarns to increase the total denier of the yarn. Plying can be carried out with the same equipment and techniques normally employed for this purpose. a

What I claim and desire to protect by Letters Patent 1. A process for intimately blending continuous filaments into a yarn comprising: v

providing at least two films each having a plurality of parallel longitudinal striations;

fibrillating said films to at least partially separate said striations from one another to form a plurality of parallel continuous filaments; guiding the filamentsof one film to uniformly mix with the filaments of said other film; and forming the mixed filaments into a yarn. 2. The process of claim 1 wherein the mixed filaments are formed into a yarn by twisting.

3. The process of claim 1 wherein the mixed fila-" ments are formed into a yarn by entanglement.

4. The process of claim 1 wherein said films are fibrillated t0 form a plurality of parallel continuous filaments which are substantially unconnected to one another.

5. A process for preparing yarn comprising:

providing at least two films each having a plurality of spaces between the filaments of the first film to uniformly mix the filaments; and forming said mixed filaments into a yarn.

6. The process of claim 5 Wherein the filaments of one of the films are of a different size than the filaments of the other film.

7. The process of claim 5 wherein the films are prepared from polymers having different shrinkage potential and including the additional step of shrinking the yarn to provide bulk in the yarn.

8. The process of claim 5 wherein the polymer of one film is polypropylene and that of the other film is polypropylene which has been subjected to controlled thermal degradation. 

1. A process for intimately blending continuous filaments into a yarn comprising: providing at least two films each having a plurality of parallel longitudinal striations; fibrillating said films to at least partially separate said striations from one another to form a plurality of parallel continuous filaments; guiding the filaments of one film to uniformly mix with the filaments of said other film; and forming the mixed filaments into a yarn.
 2. The process of claim 1 wherein the mixed filaments are formed into a yarn by twisting.
 3. The process of claim 1 wherein the mixed filaments are formed into a yarn by entanglement.
 4. The process of claim 1 wherein said films are fibrillated tO form a plurality of parallel continuous filaments which are substantially unconnected to one another.
 5. A process for preparing yarn comprising: providing at least two films each having a plurality of parallel longitudinal striations; fibrillating said films to form a plurality of parallel continuous filaments; displacing the parallel filaments of at least one film to provide sufficient space between adjacent filaments to accommodate therebetween the filaments of the other film; guiding the filaments of the second film into the spaces between the filaments of the first film to uniformly mix the filaments; and forming said mixed filaments into a yarn.
 6. The process of claim 5 Wherein the filaments of one of the films are of a different size than the filaments of the other film.
 7. The process of claim 5 wherein the films are prepared from polymers having different shrinkage potential and including the additional step of shrinking the yarn to provide bulk in the yarn.
 8. The process of claim 5 wherein the polymer of one film is polypropylene and that of the other film is polypropylene which has been subjected to controlled thermal degradation.
 9. The process of claim 5 wherein the filaments of one of the films are of a different color than the filaments of the other film.
 10. The process of claim 5 wherein the filaments are formed into a yarn by twisting.
 11. The process of claim 5 wherein the filaments are formed into a yarn by entanglement.
 12. The process of claim 5 wherein one film is of a different material than the other film. 